The document studied the oxidative desulphurization of model fuels like benzothiophene (BT) and dibenzothiophene (DBT) using metal-impregnated Ti-β catalysts. Four metals - Ag, Cu, Sn, and Mo - were impregnated on Ti-β zeolite at different concentrations. Characterization showed the Ti-β catalyst was crystalline with a BET surface area of 55.965 m2/g. Experimental results found that 2.5% Sn-impregnated Ti-β had the highest BT conversion of 66.68%, while 2.5% Cu-impregnated Ti-β achieved the highest DBT conversion of 60.92%. The effect of

1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
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OXIDATIVE DESULPHURIZATION OF MODEL FUEL BY METAL
IMPREGNATED Ti-β CATALYSTS
Sankhajit Pal 1, Biswajit Saha2, Sonali Sengupta3
1Department of Chemical Engineering, C.V. Raman College of Engineering, Bhubaneswar, Odisha, India
2Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, West Bengal, India
3Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, West Bengal, India
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Abstract - This paper showed the catalytic activity of Ti-β
zeolite and how the metal impregnationoncatalystaffectsthe
efficiency of Ti-β on oxidation of benzothiophene (BT) and di-
benzothiophene (DBT). Four metals (Ag, Cu, Sn and Mo) were
chosen and impregnated onTi-β zeolite at different
concentration. The catalyst was characterised by BET, XRD
and SEM analysis. Experimental results showed that the 2.5
weight% of Sn-impregnated and Cu-impregnated Ti-β zeolite
have highest oxidation efficiency for BT and DBT respectively
[66.68 % for BT and 60.92% for DBT] compared to Ti-β
zeolite. Finally the effect of parameters like stirrer speed,
temperature, oxidant mole ratio, catalyst loading and initial
sulphur concentration on oxidation of BT and DBT with best
metal impregnated catalysts was studied.
Keywords: - Ti-β, Oxidation, Benzothiophene, Di-
benzothiophene, metal impregnation.
1. INTRODUCTION
The sulfur compounds in fuel causes generationofSOxwhich
in turn causes acid rain & air pollution also do harm to
human health. Moreover causes poisoning of catalyst.
Therefore removal of sulfurcontainingcompoundsfromfuel
has become a major environmental concern. Generally
petroleum products are considered to contain four types of
sulfur compounds namely alkyl benzothiophenes (∼39%),
dibenzothiophenes (DBT), alkyl DBTs (∼20%) without
substitution at 4 and 6 position, alkyl DBTswithsubstitution
at 4 or 6 position (∼26%)[1-3]. Thus, very stringent
regulations for ultra-low-sulfur fuels were imposed on oil
refineries to reduce the sulfur content of fuel oils to a very
low limit about 10 to 20 ppm[4]. Normally industries apply
catalytic hydrodesulphurization (HDS) technology for
carrying out desulphurization. Oxidative Desulfurization
(ODS) as an alternative process to the traditional HDS
processes has gained much attention for deep
desulfurization of fuels due to a number of reasons. In
Comparison with conventional HDS process ODS hasmainly
two advantages. Firstly it can be carried out in liquid phase
and can be operated under mild condition. Secondly the
most refractory sulfur-containing compounds to the HDS
process, (e.g. DBT and its derivatives) show high reactivity
toward the oxidation by thismethod[5,6].Attached electron
rich aromatic ring increases electron density at the sulfur
atom which in turn causes electrophilic attack on the sulfur
atom. Alkyl groups attached to the aromatic ring also
contributes an increase in electron density. Thus, the
intrinsic reactivity of molecules like 4,6-dimethyl DBT is
substantially higher than that of DBT, and in fact the
sequence of increasing susceptibility to oxidation is exactly
opposite to that to HDS[7]. Besides,theODSprocessisa non-
hydrogen consuming desulfurization method and can be
applied whenever enough hydrogen sources are not
available. By ODS process, these refractory sulfur
compounds are oxidized to their corresponding sulfoxides
and subsequently sulfones which can be removed by a
number of separationprocessesincludingsolventextraction,
adsorption, etc.
2. Experimental Methodology
2.1 Catalyst Preparation
Ti-β was synthesized according to the procedurereported in
literature[8]. Synthesis of titanium-beta requires two
solutions, solution A and solutionB.SolutionAwasprepared
by adding 0.58 g of tetrabutylorthotitanate to 4.0 g of
distilled water and to the resulting suspension was added
2.0 g of H2O2 after 1 h. The mixture was stirred at room
temperature for 1 h, leading to solution A containing
peroxide titanate. Solution B was prepared by dissolving
0.0124 g of anhydrous NaAlO2 and 0.015 g of NaOH in 8.0 g
of tetraethylammonium hydroxide (TEAOH) at room
temperature with 1 h stirring. Solution A and B are mixed
together and stirred for 1.5 h. A clear homogeneous solution
obtained after 2 h was heated to 353 K and dried while
stirring. When the gel became dry to solid, it was ground to
fine powder and transferred intoa teflonbeakersituatedina
teflon lined special autoclave, where water (5.0 g), as a
source of steam was poured at the bottom. The
crystallization was carried out in steam at 403 K for 96h,
subsequently at 448 K for 18 h under autogenous pressure.
The recovered product was washed with distilled water,
dried at 308 K for 10 h, and calcined at 793 K for 10h in the
flow of air. The resulting Ti-beta zeolitewastreated with 1M
H2SO4 at room temperature for 12 h and then washed with
distilled water, dried at 308 K for 10 h, and calcined at 793 K
for 5 h under the air flow. The prepared Ti-β catalyst was
impregnated with varying loading of metals. Impregnation
was carried out by taking catalyst in the aqueous solution of
salt of the metal and then stirring the mixture under heating
until the whole mixture gets completely dry. The mass was
then washed, dried and calcined at 500◦
C for 5h. Finally Ti-β
catalyst impregnated with varying loading of different
metals was obtained.

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2.2 Reaction Methodology: The reaction was carried out in
a 100 ml glass reactor fitted with a glass stirrer and
condenser, kept in a water bath whose temperature was
maintained within ±1 °C accuracy by using a temperature
controller cum indicator. A typical reaction was carried out
by taking 50 ml of model fuel, a definite amount of catalyst
and TBHP(TBHP:S=10:1mole ratio) in the reactor at various
temperature under stirring at various speeds. Reaction
samples were taken out at 10 minutes of time interval. The
samples were analyzed in high performance liquid
chromatography (Perkin Elmer, Series 200) with reversed
phase Agilent SB C-18 column and conversion was
determined.
3. Results
3.1: Catalyst Characterization
XRD analysis: XRD analysis of Ti-β was performed. Fig.1
shows the XRD plot. From the XRD plot it is clear that the
prepared catalyst is crystalline in nature.
Fig.1: XRD plot of Ti-β catalyst
SEM and HRTEM images of Ti-beta zeolite
The scanning electron microscopy (SEM) image of calcined
Ti-beta catalyst is shown in Figure 2. The Ti-beta sample
appears to be highly crystallinewithuniformcrystal sizeand
no amorphous phases detected on the surface. Ti-beta
nanoparticles with regular shape can be clearly observed in
the high resolution transmission electron microscopy
(HRTEM) image (Figure 3) of calcined sample. The crystal
size of the synthesizedTi-beta calculatedfromHRTEMimage
is in the range of 20-40nm. The chemical compositionsof Ti-
beta sample are listed in Table 1 based upontheEDXresults.
Catalyst Ti/(Si+Ti+Al),
mol%
Na/(Si+Ti+Al),
mol%
Al/(Si+Ti+Al),
mol%
Ti-beta 3.115 0.616 0.445
Table 1: Chemical composition of Ti-beta zeolite.
Fig.2 SEM image of Ti-β catalyst
Fig.3 HRTEM image of Ti-β catalyst
BET of Ti-β zeolite
The multipoint Brunauer Emmett Teller (BET) analysis of
the catalysts has beendone by Quantachrome-Autosorb-1
(Model: AS1 MP/Chemi-LP). In the determinationof specific
BET surface area (SBET), the adsorbate gas used is nitrogen
since it is inertand does not react with the solid catalyst.The
samples were degassed at 200◦
C for15 min and 2 h under
high vacuum before the adsorption of nitrogen at 196◦
C was
performed. The P/P0 (where P is the equilibrium pressure
and P0 is the saturation pressure of the adsorbate gas at the
adsorption temperature) tolerance is maintained at a value
of 6. Result of BET analysis is given in Table 2.
Catalyst Avg pore
radius(Å)
BET surface
area (m2/g)
Total pore
volume(cc/g)
Ti-beta 124.18 55.965 0.345
Table 2: BET analysis of Ti-beta zeolite.

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3.2: Experimental Results:
Fig 3: conversion of BT with 1.5% metal impregnated
Ti-β
Fig 4: conversion of DBT with 1.5% metal impregnated
Ti-β
Fig 5: conversion of BT with 2.5% metal impregnated
Ti-β
Fig 6: conversion of DBT with 2.5% metal impregnated
Ti-β
Fig 7: conversion of BT with 4% metal impregnated Ti-
β
Fig 8: conversion of DBT with 4% metal impregnated
Ti-β
Conversion of BT and DBT with Mo, Cu,Sn&Agimpregnated
Ti- β catalysts was observed. It is observed that for
treatment of BT highest conversion is achieved with 2.5%
Sn/Ti-β and for treatment of DBT highest conversion is
achieved with 2.5% Cu/ Ti-β.

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Fig 9: conversion of BT with stirrer speed
Fig 10: conversion of BT with temperature
Fig 11: conversion of BT with TBHP:S ratio
Fig 12: conversion of BT with catalyst concentration
Fig 13: conversion of BT with sulphur concentration
Fig 14: conversion of DBT with stirrer speed

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Fig 15: conversion of DBT with temperature
Fig 16: conversion of DBT with TBHP:S ratio
Fig 17: conversion of DBT with catalyst concentration
Conversion of BT and DBT is observed at stirrer speed of
300, 600, 800, 1000 and 1200 rpm. It is observed that
conversion increases with stirrer speed and highest
conversion is achieved for stirrer speed of 1200 rpm.
Conversion of BT and DBT is observed at temperature of
30◦
C, 40◦
C, 50◦
C, 60◦
C and 70◦
C. It is observedthatconversion
increases with temperature and highest conversion is
achieved for temperature of 70◦
C.
Conversion of BT and DBT is observed atTBHP:S ratioof2:1,
4:1, 10:1 and 20:1. It is observed that conversion increases
with TBHP: S ratio and highest conversion is achieved for
TBHP:S ratio of 20:1.
Conversion of BT and DBT is observed at catalyst
concentration .2, .6, 1, 1.5 and 2 gm/l. It is observed that
conversion increaseswithcatalystconcentrationandhighest
conversion is achieved for catalyst concentration of 2 gm/l.
Conversion of BT and DBT is observed at sulphur
concentration of 500, 800, 1000, 1500 and 2000 ppm. It is
observed that conversion decreases with sulphur
concentrationandhighestconversionisachievedforsulphur
concentration of 500 ppm.
Based on the above observations the optimum conditions
were chosen as following:
Stirrer speed: 1200rpm
Temperature: 70C
TBHP: S ratio: 20:1
Catalyst concentration: 2gm/l
4. Conclusions
Conversion of BT and DBT with Ti-β as well as metal
impregnated Ti-β was observed. Metal Loaded catalysts
were found to deactivate after a certain time and conversion
becomes constant. Best catalyst were chosen to be for BT
2.5% Sn/Ti-β and for DBT 2.5% Cu/ Ti-β. Parametric study
was also conducted. OptimumreactionconditionsareStirrer
speed: 1200rpm, Temperature: 70C, TBHP: S ratio: 20:1,
Catalyst concentration: 2gm/l. It was also observed that we
are getting highest conversion for 500 ppm sulphur
concentration.OxidationofBTandDBTwasconducted using
the best catalyst at optimum process conditions.
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Volume: 04 Issue: 08 | Aug -2017 www.irjet.net p-ISSN: 2395-0072
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